Determining ASHRAE 90.1-2010 Climate Zones

1 Information Bulletin Building and Safety Standards Branch PO Box 9844 Stn Prov Govt Victoria BC V8W 9T2 Email: Website: The contents of this Bulletin are not intended to be provided as legal advice and should not be relied upon as legal advice. For further information contact the Building & Safety Standards Branch. 1 No. B14 - 01 July 23, 2014 Determining ASHRAE Climate Zones ASHRAE Energy Standard for Buildings Except Low-Rise Residential Buildings requirements are based on the environmental conditions of the proposed building location.

2 ASHRAE requires four climatic values to define the environmental conditions of a proposed building location: Heating Degree-Days below 18 C Cooling Degree-Days above 10 C Monthly Mean Temperature Monthly Precipitation Thresholds for each of these climatic values have been established in order to group environmental conditions into various Zones . Table B-4 International Climate Zone Definitions in ASHRAE (see Appendix) provides the calculation formula for establishing Climate Zones based on these four climatic values.

3 The assigned Climate Zone dictates energy efficiency requirements appropriate to the locations. The BC Building Code states that the authority having jurisdiction (AHJ) can establish climatic values1 for use in the calculation formula provided in Table B-4. A common approach is for AHJs to use Heating Degree-Days below 18 C from listed locations (or in the absence of a specific listing, neighbouring locations) within Table C-2 Design Data for Selected Locations in Canada of the BC Building Code, and apply them broadly to all construction within their jurisdiction2.

4 Values for cooling degree-days above 10 C, monthly mean temperature, and monthly precipitation however are not provided in Table C-2. These values can be modelled by Environment Canada based on latitude and longitude as a fee-based service. Alternatively, the AHJ can obtain raw climatic data from select weather stations (available on Environment Canada s website: ), and map appropriate values based on geographic proximity and local experience. It would be reasonable if an AHJ established a set of these three values and likewise apply them broadly within their jurisdiction.

5 If the AHJ chooses not to establish climatic values, the building designer must obtain the climatic values by selecting the appropriate values from Table C-2 of the BC Building Code and by contacting Atmospheric Environment Service, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4, 416-739-4365. 1 2012 BC Building Code Sentence (1) The Climate and seismic values required for the design of buildings under this Code shall be in conformance with the values established by the authority having jurisdiction or, in the absence of such data, with Sentence (2) and the climatic and seismic values in Appendix C.

6 2 Some of the climatic values listed in Table C-2 have been interpolated or modelled from data collected at weather stations to better represent locations where construction is most predominant. Information Bulletin Building and Safety Standards Branch PO Box 9844 Stn Prov Govt Victoria BC V8W 9T2 Email: Website: The contents of this Bulletin are not intended to be provided as legal advice and should not be relied upon as legal advice. For further information contact the Building & Safety Standards Branch. 2 Frequently Asked Questions Question 1: Can I use the Climate Zones established in the 2011 National Energy Code for Buildings (NECB) as the Climate Zones for applying ASHRAE Answer: No, ASHRAE Climate Zones are not the same as the Zones defined in the 2011 NECB.

7 The thresholds for defining these Zones are derived from different values. Question 2: The AHJ is suggesting a Climate zone to use when designing my building. Do I have to use it? Answer: Some AHJs complete the calculations in ASHRAE Table B-4 based on their established climatic values. This is appropriately done as a combination of a service to designers and as an exercise of their authority under Sentence (1). Question 3: Section of ASHRAE instructs you to use the Climate Zones for some Canadian locations shown in Table B-2 Canadian Climate Zones of Appendix B (of ASHRAE ).

8 If my location is shown in Table B-2, can I use the Climate zone given in the standard? Answer: The Climate Zones listed in Table B-2 have been derived in collaboration with Environment Canada (from the values reported in Table D-2 Canadian Climatic Data of ASHRAE ) and can be viewed as a credible source. However, if the AHJ has established climatic values that differ from those given in the standard; it is the values from the AHJ that take precedence3. It should be noted that Table B-2 does not include the Climate zone letter often required to identify the zone.

9 3 2012 BC Building Code Sentence (1) In the case of conflict between the provisions of this Code and those of a referenced document, the provisions of this Code shall govern. Information Bulletin Building and Safety Standards Branch PO Box 9844 Stn Prov Govt Victoria BC V8W 9T2 Email: Website: The contents of this Bulletin are not intended to be provided as legal advice and should not be relied upon as legal advice. For further information contact the Building & Safety Standards Branch.

10 3 Appendix ASHRAE Table B-4 International Climate Zone Definitions International Climate Zone Definitions Zone Number Zone Name Thermal Criteria (I-P Units) Thermal Criteria (SI Units) 1A and 1B Very Hot Humid (1A) Dry (1B) 9000 < CDD50 F 5000 < CDD10 C 2A and 2B Hot-Humid (2A) Dry (2B) 6300 < CDD50 F 9000 3500 < CDD10 C 5000 3A and 3B Warm Humid (3A) Dry (3B) 4500 < CDD50 F 6300 2500 < CDD10 C < 3500 3C Warm Marine (3C) CDD50 F 4500 AND HDD65 F 3600 CDD10 C 2500 AND HDD18 C 2000 4A and 4B Mixed-Humid (4A) Dry (4B) CDD50 F 4500 AND 3600 < HDD65 F 5400 CDD10 C 2500 AND HDD18 C 3000 4C Mixed Marine (4C) 3600 < HDD65 F 5400 2000 < HDD18 C 3000 5A, 5B, and 5C Cool-Humid (5A) Dry (5B) Marine (5C) 5400 < HDD65 F 7200 3000 < HDD18 C 4000 6A and 6B Cold Humid (6A) Dry (6B) 7200 < HDD65 F 9000 4000 < HDD18 C 5000 7 Very Cold 9000 < HDD65 F 12600 5000 < HDD18 C 7000 8 Subarctic 12600 < HDD65 F 7000 < HDD18 C Marine (C) definition Locations meeting all four of the following criteria: 1.